Treatment of hydrocarbon oils



Dec. 3, 1935. L. A. MEKLER TREATMENT OF HYDROCARBON OILS Original Filed Nov. 22', 1950 A nql l hur l LEV A. MEKLER BY? ATTORNEY Patented Dec. 3, 1935 PATENT OFFICE TREATMENT OF HYDROCARBON OILS Lev A. Mekler, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota Application'November 22, 1930, Serial No. 497,559 Renewed March 5, 1935 I I 2 Claims. 'This invention relates to the cracking of hydrocarbon oils and refers particularly to the conheated materials from the relatively low temperature or liquid-vapor-phase heating element,'the combined materials pass to an enlarged reaction zone total products from which are withdrawn to a secondary enlarged zone preferably maintained under reduced pressure, vapors and unvaporized material are separated in the secondary enlarged zone, vapors from which are subjected to fractionation, the relatively light and the relatively :heavy portions of the insumciently converted vapors are separately condensed in the fractionating zone, the heavier portions passing together with raw oil charging stock to the relatively low temperature or liquid-vapor-pha'se heating element,

while the lighter portions are subjected to revaporization and the vapors resulting therefrom are subjected to reconversion in the relatively high temperature of vapor-phase heating element.

As a feature of the present invention the relatively light refluxcondensate from the fractionating zone,= which is to be subjected to relatiyely high temperature or vapor-phase reconversion, is preheated ,by and utilized as a cooling medium for products from the primary reaction zone by indirect contact with said products during their passage from the primary reaction zone to the secondary chamber. I 4

Another feature of the invention provides for 2 secondary chamber.

The attached diagrammatic drawing illustrates In a specific embodiment of the invention vapors from the relatively high temperature or vapor-phase heating element are combined with one specific form of apparatus'embodying the features of the present invention and the following description of the drawing embraces also a description of the process of the invention as it may be practiced in the apparatus shown.

Raw oil charging stock supplied through-line l and valve 2 to pump 3 is fed through line 4 and may pass through valve 5 into heat exchanger 6, where it is preheated by indirect contact with fractionated vapors, passing therefrom through line I and valve 8 from which it may pass through line 9 and valve In into preheating coil I I, located in fractionator 12, where it is further preheated by indirect contact with the relatively hot ascending vapors in this zone, passing therefrom through line l3 and valve H back into line I. A portion or all of the raw oil may by-pass heat exchanger 3 through line 15 controlled by valve l6. Likewise a portion or all of the raw oil may by-pass preheating coil II by passing directly through valve I'Lin line 1. Raw oilfrom line I may pass all or in part through line l8 and valve [9 into fractionator l2, preferably at a point below partition 20, where it is further preheated by direct contact with the hot ascending 25 vapors in the lower portion-of the fractionating zone, assisting their fractionation and passing together with their heavier condensed portion through line 2| and valve 22 into pump 23. From pump 23 the combined materials are fed through '30 valve 25 into line 24, combining therein with that portion, ifany, of the raw oil charging stock which may be passed through valve 26, in line 1, into pump 21 and .thence through line 28 and valve 23 into line 24. 1 Heating element 30 is located in any suitable form of furnace 3| and the oil supplied thereto through line 24 is subjected to the desired conversion conditions, preferably within the range of liquid-vapor-phase cracking, and passes therefrom through line 32, valve 33, line 34 and valve 35 into reaction chamber 36. Reaction chamber 36 may be maintained under substantially the same or under reduced pressure relative to that employed in heating element 30 and the total products from this zone including liquid and vapor are withdrawn through line 31, valve 38, heat exchanger 39, line 40 and valve ll to chamber 42;

Chamber 42 may be maintained under substan- 60 tially the same pressure or under reduced pressure relative to that employed inchamber 36 but is preferably, in all cases, maintained under a lower pressure than that employed in heating element 30. Separation of vapors and unvaporlsed mai terial is permitted in chamber 42, the unvaporized liquid is withdrawn through line 43 and valve 44, subjected to cooling in cooler 45 thereafter passing through line 46 and valve 41 to pump 48 from which it may be withdrawn all or in part from the system through line 49 and valve 50 or may be recirculated in any desired proportion through line 5| and valve 52 into line 40 combining therein with the relatively hot products from chamber 36 and cooling them to the desired degree. Vapors from chamber 42 pass through line BI and valve 82 into the lower portion of fractionator l2.

Fractionator l2, as here illustrated, is a single column which may be provided with any suitable fractionating means such as packing, bubble trays, perforated pans or the like, not shown, and is divided into two separate fractionating zones by partition '20. It will be understood that the two separate fractionating zones may employ separate columns, if so desired. Vapors introduced into fractionator i 2 from chamber 42 are first subjected to fractionation in the lower portion of the fractionator below partition 20 and that portion of the heavy insufficiently converted vapors condensed in the lower portion of the fractionator passes together with the raw oil charging stock to heating element 38, as already described. The vapors remaining uncondensed in the lower portion of the fractionator pass through partition 20 into the upper portion where they are subjected to further fractionation. Liquid, resulting from condensation in this zone, which is of lighter composition than the reflux condensate withdrawn from the lower portion of the fractionator, collects above partition 20 and is withdrawn through line 53 and valve 54 to pump 55 being thus fed through line 56, heat exchanger 38 and line 51 to heating element 58.

Heat exchanger 39 serves to cool products withdrawn from reaction chamber 36 and reheat the condensate withdrawn from the upper portion of fractionator i2. This reheated condensate is subjected to temperatures in heating element 58 sufflcient to effect its substantial vaporization and passes through line 59 and valve 60 into chamber 6|. Any unvaporized material maybe withdrawn from chamber Bi and from the system through line 62 and valve 63. Any portion or all of this unvaporized material may be diverted from line 62 through line 83 and valve 84 to pump 85 and thence fed through line 88 and valve 81 into line 82 and into the lower portion of fractionator l2. Vapors withdrawn from chamber 8! through line 54 and valve 65, are subjected to reconversion in heating element 06 under any desired conversion conditions; preferably within the range of vaporphase cracking, and pass through line 81 and valve 68 into line 34, combining therein with heated materials from heating element 30 and passing therewith through valve 35 to reaction chamber Heating elements 30, 58 and 56 are shown in one furnace structure 3| although it will be understood that separate furnace' structures may be employed for each or any of the heating elements and in any casethe arrangement of the heating elements is such that the temperature conditions in each may be independently controlled.

Fractionated vapors from fractionator I2, which are preferably within the boiling range or contain a substantial proportion of material boiling within the range of motor fuel, are withdrawn through line 69, valve 10, heat exchanger 6, line H and valve 12, are subjected to condensation and cooling in condenser I3 products from which pass through line 14 and valve 15 to be collected in-receiver I6. Distillate may be withdrawn from receiver 16 through line 11 and valve 18. Uncon densable gas may be released through line Ill controlled by valve 80. A portion of the condensed s distillate from receiver 16 may, if desired, be recirculated by well known means, not shown, to fractionator l2 to assist fractionation of the vapors in this zone.

Pressures employed within the system may 10 range from subatmospheric to super-atmospheric pressures as high as 1500 pounds or more per square inch. Substantially equalized pressure may be employed throughout the system or differential pressures may be employed between the 15 various elements. Preferably chamber 42 and subsequent portions of the system, namely, fractionator l2, condenser 13 and receiver 18 are maintained under substantially reduced pressure relative to that employed in heating element 88. 20 Conversion temperatures employed may range from 750 to 1200 F., more or less. Preferably more severe conversion conditions are employed in heating element 66 than in heating element 88 while heating element 58 may be operated at rela- 85 tively mild conversion temperatures or preferably at temperatures below the cracking range.

As a speciflc example of operating conditions which may be employed and results which may be obtained from the operation, a mid-continent 80 topped crude oil of about 30 A. P. I. gravity is the charging stock for the systemand is subjected, together with relatively heavy reflux condensate, to a temperature of about 900' I". under a superatmospheric pressure of. about 2'75 pounds per 88 square inch. The lighter reflux condensate is substantially revaporized and the vapors are subiected to reconversion at a temperature of about 1000 F. under a pressure of about poimds per square inch. The primary reaction zone is'mnin- 4o tained under a substantially equalized pressure of approximately I00 pounds per square inch, and the products withdrawn therefrom to the secondary chamber are cooled to a temperature of about 800 F. by indirect contact with the rela- 45 tively light reflux condensate and by recirculation of unvaporized residual oil from the-secondary chamber. The secondary chamber, the iractionator and the condensing and collecting equipment are maintained under a substantially 60 equalized pressure of about 30 pounds per square inch. An operation such as outlined may yield about 60% of motor fuel having an anti-knock value equivalent to a blend of about 60% bennol and about 40% Pennsylvania straight run gaso- 68 line and in addition a yield of about 23% of fuel oil as the residual product from the system.

What is claimed is:

1. A hydrocarbon oil cracking process which comprises introducing vapors, formed as herein- 00 after set forth, to a fractionating none and fractionating the same therein in contact with charging oil for the process thereby forming a mixture of charging oil and primary reflux, further fractionating the vapors out of contact with the charging oil to form a relatively light secondary reflux, passing said mixture through a heating zone and heating the same therein to cracking temperature under suflicient pressure to maintain a substantial portion thereof in liquid phase, (0 simultaneously vaporizing a substantial portion of said secondary reflux and heating the resultant vapors independently of and to a higher cracking temperature than said mixture, intrw ducing the thus heated vapors and the hosted 15 a, substantial portion thereof in liquid phase.

mixture into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing the vaporous and liquid conversion products as a mixture from the reaction zone and lowering the pressure thereon, separating the conversion products into vapors and residue under the reduced pressure, supplying to vaporous conversion products to the fractionating zone as the first-mentioned vapors, and finally condensing the fractionated vapors.

2. A hydrocarbon oil cracking process which comprises introducing vapors, formed as hereinafter set forth, to a fractionating zone and fractionating the same therein in contact with charging oil for the process thereby forming a mixture of charging oil and primary'refiux, further fractionating the vapors out of contact with the charging oil to form a relatively light secondary reflux, passing said mixture through a heating zone and heating the same therein to cracking temperature under suflicient pressure to maintain simultaneously vaporizing a substantial portion of said secondary reflux and heating the resultant vapors independently of and to a higher cracking temperature than said mixture, passing the heated mixture from said heating zone through a reaction zone maintained under cracking conditions of temperature and pressure and discharging resultant vapors and liquid conversion products as a mixture into a separating zone maintained under lower pressure than the reaction zone, also introducing to the separating zone the vaporous conversion products formed by the independent heating of the vapors of said secondary reflux, separating the commingled vaporous conversion products from residue in the separating zone and supplying the former to the fractionating zone as the first-mentioned vapors, and finally condensing the fractionated vapors.

LEV A. MIEKLER. 

